The victim was assaulted in Castle Square, Brighton, shortly before 5am on Sunday (10 August) and left fighting for his life.
The suspect is a black man aged 22 to 26 who was wearing a dark hooded top and jeans at the time. He ran off through Pavilion Gardens.
Shortly afterwards he got into a Brighton and Hove green and white taxi and was taken to Worthing.
Police were told about the attack by a man with a guitar. He was wearing a black and grey chequered coat with the hood up and was carrying the instrument in a black guitar case on his back.
Detective Sergeant Julie Greenwood said: “The man with the guitar alerted our officers to the fact that the victim had been hurt and that it appeared serious. This may well have saved the victim’s life.
“He may have seen the attack taking place and will hopefully be able to identify the suspect as they were in a newsagents at the same time moments earlier. We need to speak to him.”
Detectives are also still trying to trace a taxi driver who took the suspect to Durrington or Lower Salvington in Worthing between 5am and 6am after the attack.
The taxi driver had a Middle Eastern appearance and was driving a green and white Brighton and Hove taxi.
DS Greenwood said: “I cannot underestimate how important it is that the taxi driver comes forward to speak to us. He holds key information that may be crucial to bringing the offender to justice for this.”
Police would also like to speak to anyone who was in Castle Square next to the NatWest bank when the attack happened and who saw the incident or what happened in the minutes before or after it.
Anyone with information should email email@example.com quoting Operation Bunker, call 101 or contact the independent charity Crimestoppers anonymously on 0800 555111.
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